NLL: suggested rewritten input types should preserve user-written lifetimes when needed

[pnkfelix]

While working on #52663, I saw a collection of cases where the .nll.stderr files shows that we are currently generating a diagnostic where we suggest the user do something like change a &-type to a &mut-type, but the problem is that in adding the mut, we seem to lose bits of the original input type that it probably needs, such as explicit lifetimes.

See for example:

rust/src/test/ui/did_you_mean/issue-39544.nll.stderr

Lines 12 to 13 in fefe816

	LL | fn foo<'z>(&'z self) {
	| -------- help: consider changing this to be a mutable reference: `&mut self`

rust/src/test/ui/did_you_mean/issue-39544.nll.stderr

Lines 37 to 38 in fefe816

	LL | fn foo2<'a>(&'a self, other: &Z) {
	| -------- help: consider changing this to be a mutable reference: `&mut self`

rust/src/test/ui/did_you_mean/issue-39544.nll.stderr

Lines 54 to 55 in fefe816

	LL | fn foo3<'a>(self: &'a Self, other: &Z) {
	| -------- help: consider changing this to be a mutable reference: `&mut Z`

rust/src/test/ui/span/borrowck-borrow-overloaded-auto-deref-mut.nll.stderr

Lines 28 to 29 in fefe816

	LL | fn assign_field2<'a>(x: &'a Own<Point>) {
	| -------------- help: consider changing this to be a mutable reference: `&mut Own<Point>`

rust/src/test/ui/span/borrowck-borrow-overloaded-auto-deref-mut.nll.stderr

Lines 60 to 61 in fefe816

	LL | fn assign_method2<'a>(x: &'a Own<Point>) {
	| -------------- help: consider changing this to be a mutable reference: `&mut Own<Point>`

rust/src/test/ui/span/mut-arg-hint.nll.stderr

Lines 12 to 13 in fefe816

	LL | pub fn foo<'a>(mut a: &'a String) {
	| ---------- help: consider changing this to be a mutable reference: `&mut std::string::String`

rust/src/test/ui/trivial-bounds-inconsistent-copy-reborrow.nll.stderr

Lines 4 to 5 in fefe816

	LL | fn reborrow_mut<'a>(t: &'a &'a mut i32) -> &'a mut i32 where &'a mut i32: Copy {
	| --------------- help: consider changing this to be a mutable reference: `&mut &mut i32`

rust/src/test/ui/trivial-bounds-inconsistent-copy-reborrow.nll.stderr

Lines 12 to 13 in fefe816

	LL | fn copy_reborrow_mut<'a>(t: &'a &'a mut i32) -> &'a mut i32 where &'a mut i32: Copy {
	| --------------- help: consider changing this to be a mutable reference: `&mut &mut i32`